ZDoom

Gez wrote:You can define up to 255 lock numbers in [wiki]LOCKDEFS[/wiki]. So you could have 255 different keys in a single map without problems.

In fact, you can have even more unique keys than that, but you are limited to 255 locks. That means that some keys would be redundant, or perhaps some locks would require multiple keys, or perhaps some keys would not open any lock at all. If that's not enough, you can also define up to 256 [wiki=Classes:PuzzleItem]Puzzle Items[/wiki] that can work largely like keys. And then an unlimited number of other token inventory items that you can check with scripts. If you want to make a map where you have to collect 10 000 different items in order to open all the doors, you technically can. (You'll probably get bored out of your mind designing it before it's 1% complete, but that's a different issue.)

For PrBoom, you're limited to Boom's locks. That means you have the following locks only:

• Red lock (vanilla: skull or key)
• Yellow lock (vanilla: skull or key)
• Blue lock (vanilla: skull or key)
• All colors lock (Boom, skull or key)
• Red skull lock (Boom)
• Yellow skull lock (Boom)
• Blue skull lock (Boom)
• Red card lock (Boom)
• Yellow card lock (Boom)
• Blue card lock (Boom)
• All keys lock (Boom: all six keys)

Note that the Boom locks are only available in Boom's generalized locked door type. They didn't add separate locked door specials for these combinations.

• Red lock (vanilla: skull or key)
• Yellow lock (vanilla: skull or key)
• Blue lock (vanilla: skull or key)
• All colors lock (Boom, skull or key)
• Red skull lock (Boom)
• Yellow skull lock (Boom)
• Blue skull lock (Boom)
• Red card lock (Boom)
• Yellow card lock (Boom)
• Blue card lock (Boom)
• All keys lock (Boom: all six keys)